The cell body of a neuron (also called the soma) is enclosed by a plasma membrane.

Here's why this is important:

* Protection: The plasma membrane acts as a barrier, separating the internal environment of the cell body from the external environment.

* Regulation: It controls what enters and exits the cell, maintaining the proper balance of ions, nutrients, and waste products.

* Communication: It contains receptors that allow the cell to receive signals from other neurons.

While the plasma membrane is the primary enclosing structure, there are other components:

* Cytoplasm: The fluid inside the cell body that contains organelles like the nucleus, mitochondria, and ribosomes.

* Nucleus: Contains the cell's genetic material (DNA).

* Other organelles: These structures are responsible for various cellular functions, including energy production, protein synthesis, and waste removal.

So, while the cell body is technically "enclosed" by the plasma membrane, it also contains a variety of other structures that are essential for its function.